1. The Field of the Invention
This invention relates to medical devices used to repeatedly obtain blood samples from a patient by way of an indwelling infusion line.
2. The Background Art
In many cases, the condition of a patient requires that an intravenous/intraarterial tube or catheter be inserted into a blood vessel. The patient's blood vessel is connected by the tube to a source of fluid which provides fluid such as a medicament, and which is also connected to a pressure transducer which senses the pressure within the patient's blood vessel.
In critical care situations, it is necessary to periodically obtain samples of the patient's blood. Importantly, each procedure carried out using a needle stick increases the likelihood of a health care worker being inadvertently stuck and thereby being infected from a contaminated needle. Rather than stick a patient with a needle each time blood must be drawn, it is preferred that blood be drawn through the tube already connected to the patient's blood vessel. Since the tube connected to the patient's blood vessel contains fluid other than blood, such as saline solution and some medication, it is necessary to draw the patient's blood up into the tube so that a blood sample can be obtained which is substantially unadulterated by the fluid which is being supplied to the tube by an external source. Once substantially unadulterated blood has been drawn up the tube to a sampling site, the blood sample can be collected into a sample container.
Several devices have been proposed to draw blood up the tube connected to a patient's blood vessel to a sampling site. All of the proposed devices utilize a vacuum creating structure in communication with the tube to draw blood out of the patient's blood vessel up to, and past, a sampling site on the tube. Disadvantageously, many of the previously available devices require two-handed operation by a medical practitioner. Some of the previous devices utilize a conventional medical syringe to create the suction necessary to draw the blood up the tube. Such syringes are often unwieldy to use and their typical long, narrow dimensions makes them cumbersome. Many of the previously available devices are complicated and expensive. Moreover, some of the previously available devices include sharp bends in the fluid path and/or relatively long supplementary fluid paths both of which result in residual blood and fluid remaining in the fluid path which can cause problems such as clotting.
In view of the forgoing, it would be an advance in the art to provide a blood sampling system which overcomes the difficulties and disadvantages present in the previously available devices.